Receiver with light-trapping nanostructured coating: A possible way to achieve high-efficiency solar thermal conversion for the next-generation concentrating solar power

To improve the receiver's solar-thermal conversion efficiency at high temperature for the next-generation concentrating solar power (CSP), a receiver with the light-trapping nanostructured coating is proposed herein. However, for the CSP plant with the light-trapping nanostructure coated receiver, the scale of the heliostat field is on the order of meters (similar to 10m), the solar receiver tube on the order of millimeters (similar to 10 mm), and the light-trapping coating on the order of nanometers (similar to 100 nm). The whole system spans nine orders of magnitude, which makes it extremely complicated and difficult to evaluate the receiver's optical and thermal performance. To solve this problem, a multi-scale model is proposed by combining Monte Carol Ray tracing method (MCRT), finite difference time domain (FDTD) method, and finite volume method (FVM). Then, the influences of three typical light-trapping nanostructured coatings, including pyramid nanostructure, moth-eye nanostructure, and cone nanostructure, on the receiver's optical-thermal performance are studied. Among these three typical nanostructures, the cone nanostructure can maximize the receiver's optical-thermal performance, with a receiver efficiency more than 88%, which is higher than that of the commercial Pyromark2500 coating by 6e10% points. The study demonstrates that the receiver with light-trapping nanostructured coatings can achieve high receiver efficiency for the next-generation CSP. (c) 2021 Published by Elsevier Ltd.